Masticatory function assessment for patients with non-sagittal discrepancies using MAI (Mixing Ability Index) and FIA (Food Intake Ability)

Abstract

To assess masticatory efficiency in patients with non-sagittal discrepancies, static and dynamic objective measurements and subjective evaluation were carried out. The maximum bite force and the contact area using Dental Prescale® system as a static objective assessment, Mixing Ability Index (MAI) as a dynamic objective evaluation, and Food Intake Ability (FIA) as a subjective assessment were analyzed from 21 subjects (13 men and 8 women; mean age 24.62 years) in normal occlusion (Group N) and 64 patients with posterior crossbite (Group C), anterior openbite (Group O), or both (Group B). The differences of the maximum bite force, the contact area, the MAI and the FIA were compared and their correlations were figured out. The results of the present study were as follows;1.The maximum bite force, the contact area, the MAI and the FAI were significantly lower in the non-sagittal malocclusion group compared to those in the normal group (P < 0.0001).2.In both objective and subjective assessments, Group N presented better masticatory function than did those in Group C, O and B (P <0.0001), which did not differ between each other. 3.The maximum bite force and the contact area showed lower correlations with the MAI (both r = 0.24, P < 0.5), representing the limitation of static evaluation of mastication.4.The FIA showed moderate correlation with the MAI (r = 0.38, P < 0.01), implying that a subjective evaluation of mastication could be used as a simple assessment, especially with the hard foods and the selected key foods. These results revealed that masticatory function in patients with non-sagittal discrepancies is deteriorated both objectively and subjectively, suggesting a possible rationale of orthodontic treatment in terms of improvement of function.